1. Field of the Invention
The present invention relates to a zoom lens system of two lens groups, which is suitable for a taking lens of a camera to cover a superwide-angle area.
2. Description of the Related Art
A zoom lens to be used for a compact camera has a variable-power ratio of about two times and is different from a zoom lens to be used for a single-lens reflex camera. As to the zoom lens of the compact camera, since a long back focus is not necessary, the lens structure thereof is a two-group structure comprising a positive first lens group and a negative second lens group, which are arranged in order from an object side. In virtue of this structure, it is possible to shorten the total length and the back focus. Meanwhile, it is known that a wide angle of view is obtained without enlarging a lens diameter when an object-side surface of a first lens is a concave surface. By adopting this kind of the lens structure, both of downsizing and the wide angle of view are realized (see the following patent documents, for instance).
[Patent Document 1]
Japanese Patent Laid-Open Publication No. 6-82696
[Patent Document 2]
Japanese Patent Laid-Open Publication No. 2001-343586
[Patent Document 3]
Japanese Patent Laid-Open Publication No. 7-146439 (Japanese Patent Publication No. 3264067)
With respect to the conventional lenses, however, the overall angle of view at a wide-angle side is about 75°. When applying a wider-angle lens, it is impossible to sufficiently correct various aberrations of marginal lumination, distortion and so forth.